The Natural History of Western Massachusetts. By Stan Freeman and Mike Nasuti.
It doesn't delve too deeply into any specific topic, but it is a good, factual, get-to know-the-area, quick reference book. Unfortunately they didn't make it pocket-size, like a field guide type book. But you could probably throw it into a backpack pretty easily.
There are also little tidbits of useful info and factoids scattered throughout, like "the science of butterfly wings" or winter survival strategies of plants and animals, or "skunk-spray warning signs".
The last page says some of the material in the book is based on articles that have appeared in the Republican newspaper of Springfield. It is published by Hampshire House in Florence.If you enjoy the valley, you'll enjoy this book.